No one who has read a classic British detective novel, or seen any movie depicting Scotland Yard's detectives going diligently about their work, can have missed them: the distinctive letters on the collar of uniformed officers marking them by division. Even if the collars aren't mentioned, references such as "have to ring up C division," while they have the sound of authentic police jargon, raise a question: Where exactly is "C division"? Happily, there exists a map of these divisions as they stood in 1929, prepared by J.F. Moylan for his book on Scotland Yard -- and here it is, along with a key to the divisions. Alas, since the MEPO switched to the "borough policing model" in 1999, these lettered divisions are no longer in existence.